02 Seville STS - Bose inop except for chimes + clock flashing

New Cadillac guy here. I introduced myself on the Seville forum a couple of days ago. This 2002 STS has the single CD/cassette Bose and it does not work. The car had a bad battery, runs down to zero if left for a few days. Not saying there isn't an abnormal drain somewhere, but the battery really is bad. Charges to about 50 percent, shows signs of swelling. Replacing it today. The chimes work, but the Bose does not react to the "power on" button. The clock is flashing, and at night you can see that the unit's background lighting flashes too, but in opposing sync with the clock. Clock setting procedure does not work, but the random time it displays advances normally. I originally thought (as I pondered the purchase) it was a Theftlock activation caused by low voltage. But after reading about these systems, I know that "LOC" should be displayed if Theftlock is indeed active. I tried the generic GM Theftlock code retrieval button sequence, just in case the Seville is different. No reaction at all - still a flashing clock. I have tried all these things both with key "on" with the best battery charge I've had, plus with the engine running and battery voltage showing about 14V with the alternator feeding. I gather the chimes pass through the sound system in some fashion on these cars. So some degree of functionality seems to exist. Any ideas?

Re: 02 Seville STS - Bose inop except for chimes + clock flashing

This post sounds very familiar with another from the Seville area. I believe I mentioned on that post your HU does not receive the VIN information from DIM. Pull your codes, check your DIM. The HU works fine as it reacts to the chime requests from the modules on the data line yet there is no communication with the DIM. DIM is the one returning the VIN when HU request it (at startup) and also the DIM is the one storing the clock (the HU is just a display and nothing else).
Are your DIM related functions operational?